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Convection in a fully immersed granular slurry
M Medved1, H M Jaeger, S R Nagel
1James Franck Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA.
Summary
Vertical vibrations induce convection in wet granular systems. Convection velocity depends on depth, differing significantly from dry systems, with a power-law fit proving superior.
Area of Science:
- Physics
- Fluid Dynamics
- Granular Materials
Background:
- Granular systems are complex media exhibiting unique flow properties.
- Convection in granular materials can be induced by external forcing, such as vibrations.
- Understanding the dynamics of granular convection is crucial for various applications.
Purpose of the Study:
- To investigate the induction and characteristics of convection in a fluid-immersed granular system using vertical vibrations.
- To analyze the depth dependence of convection velocity in both wet and dry granular systems.
- To compare the vibrational frequency and acceleration amplitude effects on convection in wet versus dry conditions.
Main Methods:
- Inducing convection in a fluid-immersed granular system within a cylindrical container using vertical vibrations.
- Employing tracer particles to measure rise times at various depths along the central axis.
- Fitting the particle rise time data to functional forms to determine convection velocity and its depth dependence.
Main Results:
- Convection was established in a single convection roll, with upward movement in the center and downward along the walls.
- Significant differences in frequency and acceleration amplitude dependence of convection were observed between wet and dry granular systems.
- A power-law functional form provided a better fit for the depth dependence of convection velocity in wet systems compared to the logarithmic form used for dry systems.
Conclusions:
- Vertical vibrations effectively induce convection in fluid-immersed granular systems.
- The presence of fluid significantly alters the convective behavior and its dependence on vibrational parameters.
- The power-law relationship offers a more accurate description of convection velocity in wet granular systems.
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